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First published online August 3, 2006
Journal of Experimental Biology 209, 3234-3240 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02376

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Hydrogen sulfide mediates hypoxia-induced relaxation of trout urinary bladder smooth muscle

Ryan A. Dombkowski^1,2, Meredith M. Doellman², Sally K. Head² and Kenneth R. Olson^1,2,*

¹ South Bend Center for Medical Education, Indiana University School of Medicine, University of Notre Dame, Notre Dame, IN 46556, USA
² Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA

View larger version (19K): [in a new window]   Fig. 1. Typical tracings of the effects of 1 mmol l-1 H2S (as NaHS) on un-stimulated (A) and 10 µmol l-1 carbachol (CARB)-pre-contracted (B) trout bladders and the effects of hypoxia (N2) on un-stimulated (C) and CARB-pre-contracted (D) bladders. C also shows the effect of 10 mmol l-1 of cystathionine -lyase inhibitor, D,L-propargylglycine (PPG; N=4) on un-stimulated bladders before and after exposure to N2. Scale bars, force-time scale for A and C (left), B and D (right).

View larger version (18K): [in a new window]   Fig. 2. Comparison of the relaxation efficacy of 1 mmol l-1 H2S (as Na2S) and hypoxia (N2) on 10 µmol l-1 carbachol (CARB)-, 80 mmol l-1 KCl- and 80 mmol l-1 potassium acetate (KAc)-contracted trout urinary bladders (all N=8) and the effects of H2S application on a pre-existing N2 exposure and of N2 application on a pre-existing H2S exposure in pre-contracted bladders (all N=4). H2S (as NaHS) relaxation of CARB-contracted vessels is also shown. Values are means ± s.e.m. H2S was significantly less efficacious on KCl-contracted bladders than bladders pre-contracted with either CARB or KAc (). Bladders relaxed with either H2S or N2 did not respond to the other (N2 or H2S, respectively), irrespective of the pre-contractile agonist (*). There was no difference in the relaxation produced by Na2S and NaHS.

View larger version (28K): [in a new window]   Fig. 3. Effects of K+ channel inhibitors 4-aminopyridine (4-AP; 100 µmol l-1; N=4), apamin (APA,100 nmol l-1; N=4), charybdotoxin (CTX; 50 nmol l-1; N=4) and APA and CTX in combination (N=4) on a 10 µmol l-1 carbachol contraction (left) or on a 1 mmol l-1 H2S (as Na2S)-induced relaxation of a 10 µmol l-1 carbachol prestimulated bladder (right); all controls, N=8. Values are means ± s.e.m. The inhibitors had no significant effect on either the CARB contraction or the H2S relaxation.

View larger version (27K): [in a new window]   Fig. 4. Effects of Cl- channel/exchange antagonists, glibenclamide (GLY; 10 µmol l-1; N=4), 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt hydrate (DIDS; 400 µmol l-1; N=4), and tamoxifen (TAM; 100 µmol l-1; N=4) on a 10 µmol l-1 carbachol contraction (left) or a 1 mmol l-1 H2S (as Na2S)-induced relaxation of a 10 µmol l-1 carbachol-prestimulated bladder (right); all controls, N=8. Values are means ± s.e.m. DIDS significantly (*) reduced the CARB contraction; there were no other significant differences.

View larger version (16K): [in a new window]   Fig. 5. Twenty-four hour production of H2S by trout in the presence of no inhibitors (Control), the cystathionine -lyase inhibitor, D,L-propargylglycine (PPG; 20 mmol l-1) or the cystathionine ß-synthase inhibitor, amino-oxyacetic acid (AOA; 1 mmol l-1). Values are means ± s.e.m. *Significantly different from control; significantly different from control and PPG; all samples were from pooled bladders and analyzed in triplicate.

View larger version (18K): [in a new window]   Fig. 6. Effects of inhibitors of H2S synthesis on hypoxic (N2) relaxation of pre-contracted bladders. The cystathionine -lyase inhibitor, D,L-propargylglycine (PPG; 20 mmol l-1) significantly decreased a N2 relaxation of 10 µmol l-1 carbachol-pre-contracted bladders and a mixture of PPG and the cystathionine ß-synthase inhibitor, amino-oxyacetic acid (AOA; 1 mmol l-1) significantly inhibited N2 relaxation of both 80 mmol l-1 KCl- and 80 mmol l-1 KAc-pre-contracted bladders (N=4 for all experimental groups; N=8 for controls). Values are means ± s.e.m. *Significantly different from the respective control; significantly different from all other conditions.